This presentation is helpful for students and faculties of B. Pharm Second year. It has all the named reactions that are included in PCI syllabus in Pharmaceutical Organic Chemistry-3 (Unit -5). Every named reaction the presentation has introduction, mechanism and its application.This presentation is also useful for grade 12 students

1. ORGANIC CHEMISTRY
NAMED REACTION
B. Pharmacy - UNIT-5
Second Year, 2 semester
PRESENTED
BY
Sarita chaurasia
Assistant Professor
BNPCW, hyderabad

2. Dakin reaction
➢The oxidation of aldehydes and ketones to the corresponding phenols is
known as Dakin reaction.
➢The reaction works best if the aromatic ketone or aldehyde is electron rich.
➢The reagents used in Dakin Reaction are; Alkaline H2O2, acidic H2O2,
Peroxybenzoic acid (C2H4O3), 30% H2O2 with aryl selenium compounds as
activators and Urea-H2O2 adduct.
➢WERSA- obtained from the reaction of rice ash starch and water, with it
reaction is possible at room temperature.

3. Dakin reaction Mechanism
Mechanism-The exact mechanism is not certain, however it is analogous to
by is Baeyer-Villiger oxidation. Mechanism is as follows:
Step-1: Generation of hydroperoxide ion
Step-2: Attack of hydroperoxide ion to carbonyl carbon

4. Dakin reaction Mechanism contd....
Step-3: The resulted tetrahedreal intermediate undergo migration of aryl group
with subsequent removal of hydroxide group
Step-4: Hydrolysis of aryl formate

5. Synthetic Application of Dakin Reaction
➢The Dakin oxidation is most commonly used to synthesize benzenediols and
alkoxyphenols.
➢Catechol, for example, is synthesized from o-hydroxy and o-alkoxy phenyl
aldehydes and ketones, and is used as the starting material for synthesis of
several compounds, including the catecholamines, catecholamine derivatives,
and 4-tert-butylcatechol, a common antioxidant and polymerization inhibitor.
➢Other synthetically useful products of the Dakin oxidation include guaiacol, a
precursor of several flavonols;

6. Synthetic Application of Dakin Reaction contd....
➢In addition, the Dakin oxidation is useful in the synthesis of indole quinones,
naturally occurring compounds that exhibit high anti-biotic, anti-fungal, and
anti-tumor activities.

7. Claisen-Schidmt Condensation
➢The reaction between an aldehyde/ketone and an aromatic carbonyl
compound lacking an alpha-hydrogen (cross aldol condensation) is called
the Claisen-Schmidt condensation. for e.g. codensation of benzaldehyde
with acetaldehyde give cinnamaldehyde (α-β unsaturated carbonyl
compounds)

8. Claisen-Schmidt Condensation Mechanism
Mechanism:
Claisen-Schmidt Condensation reaction has three steps. Mechanism is as
follows:
Step-1: Acetaldehyde reacts with base and gives carbanion
Step-2: Attack of carbanion on benzaldehyde

9. Claisen-Schmidt Condensation Mechanism contd...
Step-3: Elimination of H2O to give cinnamaldehyde (α-β unsaturated
carbonyl compounds)

10. Application of Claisen-Schmidt Condensation
➢This reaction is used for synthesis of α-β unsaturated carbonyl compounds
e.g: cinnamaldehyde, dibenzalacetone
➢This reaction is used for determination of group CH2CO and CH2COCH2
➢This reaction is used for synthesis of naturally occurring compounds like
beta- ionone, piperine, flavonols etc

11. Wolff-Kishner reduction
The Wolff-Kishner reduction is an organic reaction by which aldehyde or
ketone converted to an alkane by using hydrazine, base, and thermal
conditions

12. Wolff Kishner Reduction Mechanism
Step 1-The aldehyde or ketone is reacted with hydrazine, gives hydrazone
Step 2- The terminal nitrogen atom is deprotonated and after rearrangement of
bond it gives negative charge on carbon(carbanion). Released proton attaches
itself with hydrxide ion gives water

13. Wolff Kishner Reduction Mechanism contd...
Step 3- The carbon is protonated by the water molecule.
Step 4-The terminal nitrogen is deprotonated again, this time forming a triple
bond with its neighbouring nitrogen atom,released as nitrogen gas.Similar to step
2, the released proton forms water

14. Wolff Kishner Reduction Mechanism contd...
Step 5-Similar to step 3, the carbon is protonated by water, gives hydrocarbon
product as shown. Thus the aldehyde or ketone is converted to an alkane
The rate determining step of this reaction is the bond formation of the
terminal carbon with hydrogen (in the hydrazone anion).

15. Synthetic Application of Wolff Kishner Reduction
➢ The reaction is widely used for reduction of carbonyl group into methylene
group. e.g. reduction of benzophenone to diphenylmethane
➢ Reduction of camphor to camphene

16. Birch Reduction
The Birch reduction is a reaction where aromatic compounds which have a
benzenoid ring are converted into 1,4-cyclohexadiene which have two
hydrogen atoms attached at opposite ends of the molecule
e.g. In the birch reduction, add sodium, ammonia, and any alcohol all as a
catalyst to benzene to form 1,4 cyclohexadiene

17. Birch Reduction Mechanism
Mechanism: The Birch reduction mechanism is illustrated below:
➢Step 1-The free electrons in the solution of sodium in liquid ammonia, add to the
aromatic ring, giving a radical anion(1)
➢Step 2- This radical anion is supplied with a proton by the alcohol gives neutral
radical intermediate (2)
➢Step 3- The neutral radical intermediate take free electrons and a radical step 1
(3)
➢Step 4- This radical anion is supplied with a proton by the alcohollike step 2 and
gives 1,4- cyclohexadiene

18. Birch Reduction Mechanism contd....
(1)- Radical anion from step 1
(2)- Neutral radical intermediate from step 2
(3)- Radical anion from step 3

19. Synthetic Application of Birch Reduction
➢Reduction of naphthalene give 1,4,5,8 tetrahydronapnthalene
➢This reacion is widely used for reduction of many organic compounds. e.g.
methoxybenzene into 1,4- dihydromethoxybenzene

20. Schmidt Reaction/Rearrangement
The Schmidt reaction is a reaction in which an azide reacts with a carbonyl
derivative, usually a aldehyde, ketone, or carboxylic acid, under acidic conditions
to give an amine or amide, with expulsion of nitrogen.for e.g.The reaction is
effective with carboxylic acids to give amines, and with ketones to give amides

21. Schmidt Rearrangement Mechanism
With carboxylic acid-
This mechanism begins with the formation of an acylium ion from the protonation
of the carboxylic acid followed by the removal of water.
Step 1-This acylium ion is reacted with hydrazoic acid, leading to the formation of
a protonated azido ketone.
Step 2- The protonated azido ketone and the R group undergo a rearrangement
reaction, resulting in the migration of the carbon-nitrogen bond and the removal of
dinitrogen leading to the formation of a protonated isocyanate.
Step 3- A carbamate is formed when water is introduced to attack the protonated
isocyanate.

22. Schmidt Rearrangement Mechanism contd......
Step 4- The carbamate is now deprotonated. The subsequent removal of CO2
yields the required amine.

23. Schmidt RearrangementMechanism Contd......
With aldehyde and ketone-
Step 1-This Mechanism begins with the protonation of the ketone, leading to the
formation of an O-H bond
Step 2-The subsequent nucleophilic addition of the azide leads to the formation of an
intermediate
Step 3-Water is now removed from this intermediate via an elimination reaction, forming
a temporary imine.
Step 4-An alkyl group from original ketone migrates from the carbon to the nitrogen
belonging to the imine. This results in the elimination of dinitrogen.
Step 5- Water is used to attack the resulting compound, and the subsequent
deprotonation yields a tautomer of the required amide.

24. Schmidt Rearrangement Mechanism contd......
Step 6-The relocation of a proton belonging to the tautomer of the amide gives
the final amide product.

25. Application of Schmidt Rearrangement
➢Preperation of primary amine from carboxylic acid.e.g. acetic acid gives
methyl amine
➢This reaction is most commonly used to convert differentially substituted
ketones to amides or lactams

26. Beckmann Rearrangement
➢The Beckmann Rearrangement is a reaction of the oximes that give either
nitriles or amides, depending upon the starting material.
➢These Oximes that obtained from the ketones develop into amides; oximes got
from the aldehydes shape into nitriles.
➢In this rearrangement the shift of alkyl group is always trans to migration
group[OH] e.g. Rearrangement of an oxime to an amide

27. Beckmann Rearrangement Mechanism
Mechanism:The Beckmann Rearrangement is starts with the formation of oxime
when ketone reacts with the hydroxylamine.
Step 1-The hydroxyl goup of oxime get protonated.
Step 2- The N-O bond is severed with the expulsion of water and the migration of
the alkyl substituent “trans” to the nitrogen through rearrangement .
Step 3-Isomerization process of the intermediate which adds the water molecule
on nitrogen through solvolysis
Step 4-This undergo deprotonation gives an imidate and then tautomerize to the
amide

28. Beckmann Rearrangement Mechanism contd....
Outline of mechanism is as follows

29. Application of Beckmann Rearrangement
➢This reaction is most commonly used to convert differentially substituted
ketones to amides or lactams. e.g. conversion of cyclohexanone to caprolactam
➢It is used in the industries for the synthesis of paracetamol. This integration is
achieved by the process of conversion of a ketone to ketoxime with the help of
hydroxylamine.
➢It is mainly used in the synthesis of isoquinolone from cinnamaldoxime
➢Determination of configuration of ketoximes

30. Oppenauer Oxidation
Oppenauer oxidation, named after Rupert Viktor Oppenauer, is a gentle
method for selectively oxidizing secondary alcohols to ketones. The reaction
is the opposite of Meerwein–Ponndorf–Verley reduction. The alcohol is
oxidized with aluminium isopropoxide in excess acetone.
It is an aluminium alkoxide catalyzed the oxidation of a secondary alcohol to
the corresponding ketone.

31. Oppenauer Oxidation Mechanism
Mechanism:
Step 1- The alcohol (1) coordinates to the aluminium isopropoxide2) to form a
complex (3)
Step 2- Complex (3) gets deprotonated by an alkoxide ion (4) to generate an
alkoxide intermediate (5).
Step 3- Intermediate (5) reacts with the oxidant acetone (7) and the substrate
alcohol are bound to the aluminium and formation of a six-membered transition
state (8).
Step 4- The desired ketone (9) is formed after the hydride transfer from six-
membered transition state (8).

32. Oppenauer Oxidation Mechanism contd.......

33. Application of Oppenauer Oxidation
➢ The Oppenauer oxidation is used to prepare analgesics in the pharmaceutical
industry such as morphine and codeine. For instance, codeinone is prepared
by the Oppenauer oxidation of codeine.
➢ Progesterone is prepared by the Oppenauer oxidation of pregnenolone.

34. Application of Oppenauer Oxidation contd....
➢ The Oppenauer oxidation is also used in the synthesis of lactonesfrom 1,4
and 1,5 diols
➢ Oxidation of α- ionol to α-ionone

35. Clemmensen Reduction
Clemmensen reduction is a chemical reaction described as a reduction of
ketones (or aldehydes) to alkanes using zinc amalgam and concentrated
hydrochloric acid.
This reaction is named after Erik Christian Clemmensen, a Danish chemist.

36. Clemmensen Reduction Mechanism
Mechanism:The reaction mechanism of Clemmensen reduction has not
completely been clarified, but it is well known that the alcohol is not an
intermediate.
Step 1-The reduction is thought to occur on the zinc metal surface, and involves
protonation of the carbonyl function and a concomitant electron transfer process
to give an organozinc intermediate (A).
Step 2-Further protonation of (A) followed by abstraction of water and
stepwise electron transfer yield a carbanion (B), which traps a proton
Step 3- The final stage the corresponding methylene group is formed by
exchange of the zinc with another proton.

37. Clemmensen Reduction Mechanism contd....

38. Application of Clemmensen Reduction
➢This reaction has widely used to convert a carbonyl group into a methylene
group.e.g. Reduction of acetophenone to ethylbenzene
➢To reduce aliphatic and mixed aliphatic-aromatic carbonyl compounds. e.g.
Reduction of heptanal to heptane